A key worker (6)
I believe the answer is:
typist
'a key worker' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for typist that I've seen before include "Operator of a machine that prints one character at a time" , "Worker taken from pool, perhaps" , "Someone paid to copy using a keyboard" , "Key worker" , "Stenographer" .)